Power machines, particularly walk-behind power machines, often employ an operator control handle or bail to actively control a component of the power machine. In addition to providing a means of controlling the power machine, the bail is often employed to enforce operator presence for safety reasons. For example, it is a requirement for walk-behind power mowing machines to have a “dead man” control or operator presence control, which generally includes a spring-biased bail which can be grasped by the operator during normal operation of the machine to enable the motor of the machine. If the bail is thereafter released, the machine action is rapidly terminated for reasons of safety. In the case of a “dead man” control on a lawnmower, the engine and the rotating blade are both rapidly stopped when the operator releases the bail.
More recently, blade brake clutch control apparatuses have been employed to enforce operator presence while using lawnmowers. A blade brake clutch control allows the rotating cutting blade to be stopped and engine to remain enabled when the operator releases the bail controlling the blade brake clutch. In a blade brake clutch mower equipped with an internal combustion engine, the engine can be started in a generally conventional manner, using either a rope pull or an electric starter. Once the engine is started, the engine remains running during the operation of the lawnmower unless the engine is purposely shut off by the operator. When the bail is moved to the engaged position, the blade brake clutch control activates the clutch whereby the cutting blade is engaged. Once the operator releases the control bail, a clutch between the blade and the output shaft of the engine is released and a blade brake is engaged. Thus, even though the engine continues to run, the blade comes to a stop. This action prevents the blade from freely spinning to a stop, in which an injury could occur to the user while the blade slows from an extremely high velocity of rotation.
The blade brake clutch control action can be contrasted with a dead man control mower in which the blade comes to a stop once the control bail is released since the engine is killed, i.e., engine ignition is disrupted. Nonetheless, the result is the same in both cases, namely the blade comes to a stop when the operator releases the control bail.
It is a safety requirement that bails on walk-behind lawnmowers designed for enforcing operator presence comprise a two-step apparatus such that a user must perform a two-step process before the blade can be engaged for rotation. Thus, a two-step bail apparatus for a lawnmower would provide for operator control of the mowing machine as well as conform to safety regulations. In a blade brake clutch mower, however, the control bail must operate differently than in a dead man control mower due to this need for two separate operator actions to reengage operation of the blade.
The control system used in a blade brake clutch mower to start and stop the rotation of the blade is necessarily more complex than that in a dead man control mower. Generally speaking, such a blade brake clutch control system is not as intuitively obvious to use as that for a dead man control mower. Accordingly, there is a need for a blade brake clutch control system that is simple and relatively easy to understand and use.